One vertex per element, one color per generator, with an edge from x to x·s.
(9,10)(11,16)(12,18)(13,14)(15,17)(19,24)(20,21)(22,23)(25,26,31,30)(27,34,29,32)(28,36,38,33)(35,39,37,40)(1,2,5,7)(3,4,8,6)(9,11,15,12)(10,16,17,18)(13,22,19,20)(14,23,24,21)(25,27,31,29)(26,32,30,34)(28,35,38,37)(33,39,36,40)(1,3,5,8)(2,6,7,4)(10,17)(11,12)(13,19)(21,23)(25,26,31,30)(27,32,29,34)(28,33,38,36)(35,39,37,40)(9,12,15,11)(10,18,17,16)(13,22,19,20)(14,23,24,21)(25,28)(26,33)(27,35)(29,37)(30,36)(31,38)(32,39)(34,40)(1,3)(2,4)(5,8)(6,7)(9,13,15,19)(10,14,17,24)(11,20,12,22)(16,21,18,23)(25,29,31,27)(26,32,30,34)(28,37,38,35)(33,39,36,40)(1,4)(2,3)(5,6)(7,8)(9,14)(10,19)(11,21)(12,23)(13,17)(15,24)(16,22)(18,20)(25,30,31,26)(27,32,29,34)(28,36,38,33)(35,39,37,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.